<?php

declare(strict_types=1);

namespace League\HTMLToMarkdown\Converter;

use League\HTMLToMarkdown\Coerce;
use League\HTMLToMarkdown\Configuration;
use League\HTMLToMarkdown\ConfigurationAwareInterface;
use League\HTMLToMarkdown\ElementInterface;
use League\HTMLToMarkdown\NoBreakSpaces;

class ListItemConverter implements ConverterInterface, ConfigurationAwareInterface
{
    /** @var Configuration */
    protected $config;

    /** @var string|null */
    protected $listItemStyle;

    public function setConfig(Configuration $config): void
    {
        $this->config = $config;
    }

    public function convert(ElementInterface $element): string
    {
        // If parent is an ol, use numbers, otherwise, use dashes
        $listType = ($parent = $element->getParent()) ? $parent->getTagName() : 'ul';

        // Add spaces to start for nested list items
        $level = $element->getListItemLevel();

        // A leading no-break space is kept, as whatever follows it wasn't escaped as being at the start of the line
        $value = \trim(\implode("\n" . '    ', \explode("\n", \ltrim(NoBreakSpaces::rtrim($element->getValue())))));

        // If list item is the first in a nested list, add a newline before it
        $prefix = '';
        if ($level > 0 && $element->getSiblingPosition() === 1) {
            $prefix = "\n";
        }

        if ($listType === 'ul') {
            $listItemStyle          = Coerce::toString($this->config->getOption('list_item_style', '-'));
            $listItemStyleAlternate = Coerce::toString($this->config->getOption('list_item_style_alternate', ''));
            if (! isset($this->listItemStyle)) {
                $this->listItemStyle = $listItemStyleAlternate ?: $listItemStyle;
            }

            if ($listItemStyleAlternate && $level === 0 && $element->getSiblingPosition() === 1) {
                $this->listItemStyle = $this->listItemStyle === $listItemStyle ? $listItemStyleAlternate : $listItemStyle;
            }

            return $prefix . $this->listItemStyle . ' ' . $value . "\n";
        }

        if ($listType === 'ol' && ($parent = $element->getParent()) && \is_numeric($start = $parent->getAttribute('start'))) {
            $number = (int) $start + $element->getSiblingPosition() - 1;
        } else {
            $number = $element->getSiblingPosition();
        }

        // Anything else isn't a list marker, which would leave the item's contents as part of a paragraph
        if ($number < 0 || $number > 999999999) {
            $number = $element->getSiblingPosition();
        }

        // The lines after the first only belong to the item when indented as far as the end of its marker
        $marker = $number . '. ';
        if (\strlen($marker) > 4) {
            $value = \str_replace("\n    ", "\n" . \str_repeat(' ', \strlen($marker)), $value);
        }

        return $prefix . $marker . $value . "\n";
    }

    /**
     * @return string[]
     */
    public function getSupportedTags(): array
    {
        return ['li'];
    }
}